Development of a Highly Porous Polycaprolactone (PCL) Microneedles Array Patch to Improve the Absorption of Interstitial Fluid (ISF)

In recent years, microneedle (MN) technology has attracted attention as a sensing tool for the extraction of interstitial fluid (ISF) that has various biomarkers related to our health, and analysis of such biomarkers. In our previous study, we developed a porous microneedles array patch (MAP) made of low-melting point polycaprolactone (PCL), cellulose fibers, and polyethylene glycol (PEG) as a porogen. However, there were some issues such as less porous structure on the surface of MN and defects including cracks in MN. As a result, there were several concerns that the sensing accuracy would decrease, and that the tip of the MN might remain in the skin causing inflammation during skin puncture. To solve these issues, in this study, we develop new porous MNs uisng high molecular weight of PCL with NaCl as a porogen with controlling particle sizes. By selecting a particle size of 5 μm with a NaCl content of 70%, our new MAP achieved more pores on the surface of MN and the higher mechanical strength of MN. Furthermore, we conducted animal experiments using the new porous PCL-MAP and achieved better ISF absorption performance as well as glucose sensing ability after skin puncture. From the results, it is expected that our new porous PCL-MAP can be a practical glucose sensing tool, for example, for prediabetic patients.